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CHICAGO — The newest go-to treatment for COVID-19 is a drug called Paxlovid. For people who got a prescription, they say it’s a lifesaver. Doctors agree. It’s decreased hospitalizations and serious Covid illness.

But there is a catch — some symptoms can come back and the treatment itself may cause an annoying side effect.

Dr Shivanjali Shankaran is an assistant professor infectious diseases at Rush University Medical Center

“I think it’s very helpful,” she said. “If you use the medication within five days it decrease the risk of hospitalization and progression by 88%.”

Physicians welcome Paxlovid as they learn more about its efficacy and impact.

“It can make you decrease the amount of virus you shed and if it prevents hospitalization, that’s a great feeling to have, that extra sort of extra something in our arsenal,” Shankaran said.

Paxlovid pills are a combination of Pfizer’s investigational antiviral (pf-07321332) and a low dose of ritonavir, an antiretroviral medication traditionally used to treat HIV. The treatment disrupts the replication of SARS-CoV-2 in the body by binding to an enzyme necessary for the virus to function and reproduce.

“We can hopefully prevent admissions and obviously prevent worsening symptoms,” Shankaran said. “It’s really a big deal.”

Within 24 hours after taking Paxlovid, symptoms decrease dramatically. Patients breathe better, their fever decreases, they feel less tired and achy. But days later some symptoms return. Doctors say that does not mean the drug didn’t work. The anti-viral does reduce SARS-CoV-2 levels. But when the medication wanes, lingering impacts of the virus creep back.

“Some people have been testing positive after they tested negative,” Shankaran said. “The thought is if you start treatment very, very early, your body has not yet had sort of incentive to start producing its own antibodies and potentially that might be something that’s causing this.”

A return in Covid-like symptoms still has not led to hospitalizations. A sign the medication works, even if it does leave a poor taste for some patients.

“We do have people who get this metallic taste in their mouth or just a bad taste in their mouth, so it seems to just be unfortunately one of the side effects,” Shankaran said. “Obviously not great when you’re already feeling poorly and perhaps not eating as much as you’d like to, and then your mouth taste bad as well…. (But) nothing to be alarmed about.”

Paxlovid does seem to be working so far against Covid variants. You need a prescription to get it. And some people report having trouble finding it. You can search a list of locations here.